Computer disk drives store information on magnetic disks. Typically, the information is stored on each disk in concentric tracks that are divided into sectors. Information is written to and read from a disk by a transducer that is mounted on an actuator arm capable of moving the transducer radially over the disk. Accordingly, the movement of the actuator arm allows the transducer to access different tracks. The disk is rotated by a spindle motor at high speed which allows the transducer to access different sectors on the disk.
A conventional hard disk drive (HDD) system, generally designated 10, is illustrated in FIG. 1. The HDD system 10 comprises a data storage disk 12 that is rotated by a spindle motor 14. The spindle motor 14 is mounted to a base plate 16.
The HDD system 10 also includes a drive arm assembly 18, which includes a transducer 20 mounted to a flexure arm 22. As is conventional, the transducer 20 comprises both a write head and a read head. The drive arm assembly 18 is attached to an actuator arm 24 that can rotate about a bearing assembly 26. A drive voice coil motor (VCM) 28 cooperates with the actuator arm 24 and, hence, the drive arm assembly 18, to move the transducer 20 relative to the disk 12.
The spindle motor 14, voice coil motor 28, and transducer 20 are coupled to a number of electronic circuits 30. As will be described in further detail below, the electronic circuits 30 typically include a read channel chip, a microprocessor-based controller (or combination), a random access memory (RAM) device, and associated signal drive and logic circuitry.
The disk drive system 10 typically includes a plurality of disks 12 and, therefore, a plurality of corresponding actuator arm assemblies 18. However, it is also possible for the disk drive system 10 to include a single disk 12 as shown in FIG. 1. Typically, one drive arm assembly 18 is provided for each surface of each disk 12.
FIG. 2 is a functional block diagram which illustrates a conventional disk drive such as that depicted at 10 in FIG. 1. The example hard disk drive system 10 is coupled to a host device 32 via an input/output port 34 and a power port 36. The host device 32 comprises a processor 40 and a power supply 42. The host device 32 may take many forms, including a general purpose computing device, a media player, a cellular telephone, and a digital camera or camcorder.
Data is transferred between the hard disk drive system 10 and the processor 40 of the host device 32 through the input/output port 34, and power is supplied by the power supply 42 of the host device 32 to the drive system 10 through the power port 36. The details of construction and operation of the host device 32, the input/output port 34, and the power port 36 are or may be conventional and will not be described herein beyond the extent necessary for a complete understanding of the present invention.
For a variety of reasons, the power supplied to the hard disk drive 10 through the power port 36 may be limited. As one example, the power supply 42 may comprise a power storage device, such as a battery, which has limited power storage capacity. As another example, the power may be transferred between the host device 32 and the power port 36 using a transmission system, such as a USB system, that has limited power transmission capacity, or by system specification limits.
In addition to the components of the disk drive system 10 shown and labeled in FIG. 1, FIG. 2 illustrates (in block diagram form) that the electronic circuits 30 comprise a drive controller 50, a read/write channel 52, and an interface 54. The drive controller 50 comprises a servo compensator 56. Except as noted below, the details of construction and operation of the drive controller 50, the read/write channel 52, the interface 54, and the servo compensator 56 also are or may be conventional and will not be described herein in further detail.
The disk drive system 10 is used by the host device 32 as a data storage device. The host device 32 delivers data access requests to the disk drive system 10 via the input/output port 34. The data port 34 is used to transfer data between the disk drive system 10 and the host device 32 during read and write operations.
The drive arm assembly 18 is a semi-rigid member that acts as a support structure for the transducer 20, holding it above the surface of the disk 12. The drive arm assembly 18 is coupled at one end to the transducer 20 and at another end to the drive VCM 28. The drive VCM 28 is operative for imparting controlled motion to the actuator arm 18 to appropriately position the transducer 20 with respect to the disk 12. The drive VCM 28 operates in response to a control signal generated by the servo compensator 56 of the drive controller 50. The servo compensator 56 generates the control signal in response to, among other things, an access command received from the host device 32 via the interface 54.
The read/write channel 52 is operative for appropriately processing the data being read from/written to the disk 12. For example, during a read operation, the read/write channel 52 converts an analog read signal generated by the transducer 20 into a digital data signal that can be recognized by the drive controller 50. The channel 52 is also generally capable of recovering timing information from the analog read signal.
During a write operation, the read/write channel 52 converts data received from the host device 32 into a write current signal that is delivered to the transducer 20 to “write” the data to an appropriate portion of the disk 12. The read/write channel 52 is also operative for continually processing data read from servo information stored on the disk 12 and delivering the processed data to the drive controller 50 for use in, for example, transducer positioning.
Referring now more specifically to the hard disk 12, as depicted in FIG. 2 the spindle motor 14 is operatively connected to the disk 12 such that the motor 14 rotates the disk 12 relative to the transducer 20. As the spindle motor 14 rotates the disk 12, the transducer 20 stores data on the disk 12 in substantially concentric data storage tracks 60 on a surface of the disk 12. The example data storage disk 12 also includes servo information in the form of a plurality of radially-aligned servo spokes 62 that each cross all of the tracks 60 on the disk 12. The portions of the track between the servo spokes 62 have traditionally been used to store data received from, for example, the host device 32 and are thus referred to herein as data regions 64.
In a magnetic disk drive system 10, data is stored, for example, in the form of magnetic polarity transitions within each track 60. Data is “read” from the disk 12 by positioning the transducer 20 (i.e., the read head) above a desired track 60 of the disk 12 and sensing the magnetic polarity transitions stored within the track 60 as the disk 12 moves below the transducer 20. Similarly, data is “written” to the disk 12 by positioning the transducer 20 (i.e., the write head) above a desired track 60 and delivering a write current representative of the desired data to the transducer 20 at an appropriate time.
The data storage tracks 60 are illustrated as center lines on the surface of the disk 12; however, it should be understood that the actual tracks will each occupy a finite width about a corresponding centerline. It should be understood that, for ease of illustration, only a small number of tracks 60 and servo spokes 62 have been shown on the surface of the disk 12 of FIG. 3. That is, conventional disk drives include one or more disk surfaces having a considerably larger number of tracks and servo spokes.
The servo information in the servo spokes 62 is a specialized form of data stored on the disk 12 that is read by the transducer 20 during disk drive operation for use in positioning the transducer 20 above a desired track 60 of the disk 12. In particular, the disk drive system 10 operates in at least two positioning modes: seek and track following. During the seek mode, the system 10 moves the transducer 20 from an initial track 60a to a target track 60b. During the track following mode, the system 10 maintains the transducer 20 above the desired track 60 while data is read from or written to the disk 12.
The servo information is configured to allow the system 10 to operate in both the seek and track following modes. As is well-known in the art, the servo information stored in the servo spokes allows the servo compensator 56 to determine a position of the transducer 20 relative to the disk 12. The servo compensator 56 uses the position information during seek and track following modes to move to and/or follow the target track 60b. 
Referring back for a moment to FIG. 2, it can be seen that the read/write channel comprises a preamplifier circuit 70 and a channel circuit 72. The preamplifier circuit 70 performs two functions. First, the preamplifier circuit 70 generates a write signal for driving the write head portion of the transducer 20 based on an analog differential drive signal generated by the channel circuit 72. Second, the preamplifier 70 generates an analog playback signal 72 based on a read signal generated by the read head portion of the transducer 20. The playback signal is delivered to the channel circuit 72.
The channel circuit 72 also performs two basic functions. First, the channel circuit 72 generates the analog differential drive signal based on the digital data to be written to the disk 12. Second, the channel circuit 72 converts the analog playback signal into digital data that can be processed by the drive controller 50 and/or host device 32. The details of construction and operation of the preamplifier 70 and the channel circuit 72 are or may be conventional and will not be described herein in further detail.
As generally described above, power is supplied to the hard disk drive system 10 through the power port 36. A power distribution system 80 for transmitting this power to the various electrical components of the hard disk drive system 10 is represented by bold dashed lines in FIG. 2. In addition to wiring, the power distribution system 80 may comprise circuitry for regulating the power signal obtained through the power port 36 as appropriate for each of the components of the electronic circuits 30. The example power distribution system 80 is or may be conventional and will not be described herein beyond the extent necessary for a complete understanding of the present invention.
As generally discussed above, power supplied to the hard disk drive 10 through the power port 36 may be limited, in storage capacity and/or in transmission capacity or by system specification. The electronics 30 include fully differential buffer (FDB) and complementary metal oxide semiconductor (CMOS) electronics that consume more power at relatively cold temperatures than at relatively high temperatures. Accordingly, the power consumption associated with aggressive seek operations, which are typically performed by circuits using FDB and CMOS electronics and external transistors, increases power consumption of the hard disk drive system 10. Typically the power consumption of seek operations increases as seek operations are made more aggressive.
In some cold temperature situations, the power consumption of the disk drive system 10 due to electronics and aggressive seek operations may exceed the maximum system power specifications. It is undesirable that a disk drive system exceed maximum system power specifications because these power specifications are designed based on the limitations of the power supplied to the hard disk drive system by the host device.
Accordingly, the need thus exists for hard disk drive systems and methods that limit power consumption in cold environments to ensure that the hard disk drive system design can be properly configured for the environment, power needs, usage patterns, and reliability of a particular host device.